Frontline Science: COVID-19 infection induces readily detectable morphologic and inflammation-related phenotypic changes in peripheral blood monocytes

  1. Dan Zhang
  2. Rui Guo
  3. Lei Lei
  4. Hongjuan Liu
  5. Yawen Wang
  6. Yili Wang
  7. Hongbo Qian
  8. Tongxin Dai
  9. Tianxiao Zhang
  10. Yanjun Lai
  11. Jingya Wang
  12. Zhiqiang Liu
  13. Tianyan Chen
  14. Aili He
  15. Michael O’Dwyer
  16. Jinsong Hu

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Abstract

Excessive monocyte/macrophage activation with the development of a cytokine storm and subsequent acute lung injury, leading to acute respiratory distress syndrome (ARDS), is a feared consequence of infection with COVID-19. The ability to recognize and potentially intervene early in those patients at greatest risk of developing this complication could be of great clinical utility. In this study, we performed flow cytometric analysis of peripheral blood samples from 34 COVID-19 patients in early 2020 in an attempt to identify factors that could help predict the severity of disease and patient outcome. Although we did not detect significant differences in the number of monocytes between patients with COVID-19 and normal healthy individuals, we did identify significant morphologic and functional differences, which are more pronounced in patients requiring prolonged hospitalization and intensive care unit (ICU) admission. Patients with COVID-19 have larger than normal monocytes, easily identified on forward scatter (FSC), side scatter analysis by routine flow cytometry, with the presence of a distinct population of monocytes with high FSC (FSC-high). On more detailed analysis, these CD14+CD16+, FSC-high monocytes show features of mixed M1/M2 macrophage polarization with higher expression of CD80+ and CD206+ compared with the residual FSC-low monocytes and secretion of higher levels of IL-6, IL-10, and TNF-α, when compared with the normal controls. In conclusion, the detection and serial monitoring of this subset of inflammatory monocytes using flow cytometry could be of great help in guiding the prognostication and treatment of patients with COVID-19 and merits further evaluation.

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  1. Version published to 10.1002/jlb.4hi0720-470r
  2. ScreenIT

    SciScore for 10.1101/2020.03.24.20042655: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Institutional Review Board StatementIRB: This study was approved by the Ethics Commissions of Xi’an No.8 Hospital and the First Affiliated Hospital of Xi’an Jiaotong University (2020-07), with a waiver of informed consent due to a public health outbreak investigation.
    Consent: This study was approved by the Ethics Commissions of Xi’an No.8 Hospital and the First Affiliated Hospital of Xi’an Jiaotong University (2020-07), with a waiver of informed consent due to a public health outbreak investigation.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.
    Cell Line Authenticationnot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    Flow cytometry analysis: For membrane staining, 50 μL K3-EDTA anti-coagulant whole blood cells were incubated with a panel of fluorochrome-labeled antibodies or unstained/FMO (fluorescence minus one) controls for 15 min at room temperature.
    unstained/FMO
    suggested: None
    Experimental Models: Cell Lines
    SentencesResources
    Briefly, human monocytic cell lines THP-1 and U939, as well as murine macrophage cell line RAW264.7 were cultured in RPMI1640 medium supplemented with 10% FBS (fetal bovine serum) and antibiotics, or high glucose DMEM medium supplemented with 10% FBS but without antibiotics (for RAW264.7), at 37□ in a 5% CO2 air incubator.
    THP-1
    suggested: None
    RAW264.7
    suggested: None
    Software and Algorithms
    SentencesResources
    After washing cells by adding 2 to 3 mL PBS and centrifuge for 5 min at 400g, the cells were resuspended in 400 μL PBS and examined by a flow cytometer (BD FACScantoTM II, BD Biosciences, San Jose, CA, USA) using the FACSDiva v.
    FACSDiva
    suggested: (BD FACSDiva Software, RRID:SCR_001456)
    The data were analysed by FlowJo software (Version 7.6.1; Tree Star, Inc., Ashland, OR, USA).
    FlowJo
    suggested: (FlowJo, RRID:SCR_008520)
    Data were analyzed by using GraphPad Prism version 6.04 (GraphPad Software, San Diego, CA, USA).
    GraphPad Prism
    suggested: (GraphPad Prism, RRID:SCR_002798)
    GraphPad
    suggested: (GraphPad Prism, RRID:SCR_002798)

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    While we acknowledge the limitations of our study, given the small sample size, we feel nevertheless that our findings could be of great help in guiding prognostication and treatment of patients with COVID-19 and merit further evaluation and confirmation in future studies.

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: Please consider improving the rainbow (“jet”) colormap(s) used on pages 12, 13, 15, 16 and 17. At least one figure is not accessible to readers with colorblindness and/or is not true to the data, i.e. not perceptually uniform.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    About SciScore

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.

  3. Version published to 10.1101/2020.03.24.20042655v1 on medRxiv